1. Technical Field
The present invention relates generally to semiconductor manufacturing, and more particularly, to the inspection of semiconductor photo masks.
2. Related Art
In semiconductor manufacturing, photo masks used in the fabrication of semiconductor devices may be added and/or replaced throughout processing. The additional/replacement photo mask, however, must pattern images at the wafer level that are identical to the images formed by the previously used photo mask. For ease of comparison, the images are typically formed side by side on a single wafer using both the additional/replacement photo mask and the previously used photo mask.
Heretofore, the images were compared by applying a first photo resist to a first region of a wafer, exposing the first photo resist using a first mask within the first region, developing the first photo resist, etching a first image into an etchable layer of the first region, and stripping the excess photo resist. A second photo resist was then applied to a second region of the wafer, the second photo resist was exposed using a second mask within the second region, and the second photo resist was developed. Thereafter, the etched image in the first region was compared to the photo image in the second region. This process was time consuming due to the numerous processing steps and equipment required to form each image. Accordingly, there exists a need in the semiconductor industry for a method of quickly and effectively comparing photo masks.
A first general aspect of the present invention provides a method of comparing a first photo mask and a second photo mask, comprising: providing a substrate; applying a first resist on a surface of the substrate; removing a portion of the first resist from the surface of the substrate; applying a second resist on the surface of the substrate; patterning a first image within the first resist using the first photo mask; patterning a second image within the second resist using the second photo mask; and comparing the first image and the second image.
A second general aspect of the present invention provides a method of comparing a first photo mask and a second photo mask, comprising: providing a substrate; applying a first resist in at least one first region of the substrate; applying a second resist in at least one second region of the substrate; patterning a first image within the first resist using the first mask; patterning a second image within the second resist using the second mask; and comparing the first and second patterned images.
A third general aspect of the present invention provides a method of comparing patterned images comprising: providing a substrate; applying a first resist in a substantially circular pattern; applying a second resist in substantially circular ring pattern surrounding the first resist; patterning the first and second resists to form a first and a second patterned image; and comparing the first and second patterned images.
The foregoing and other features of the invention will be apparent from the following more particular description of the embodiments of the invention.